There exists a variety of known methods for the manufacture of epichlorohydrin. These are summarized in U.S. Pat. No. 4,944,847, incorporated herein by reference. This patent describes many commonly used methods for manufacturing epichlorohydrin, such as by reacting an allylchloride with chlorine water to yield an isomeric glycerol chlorohydrin mixture which is dehydrochlorinated with an alkali material to form epichlorohydrin, which is subsequently isolated and purified by steam stripping and distillation. In an alternative method, the chlorohydrin can be made by chlorinating acrolein followed by reduction of the resulting aldehyde to form a dichlorohydrin, which is then dehydrochlorinated to form epichlorohydrin. Other methods include epoxidation of an allylchloride or oxidation of an allylchloride with air.
In each of these processes, a crude epichlorohydrin product containing impurities such as unreacted monomers or byproducts requires subsequent processing to isolate and purify epichlorohydrin. The purification of epichlorohydrin is typically accomplished through a distillation process or by other known separation techniques which produce a stream having a higher concentration of epichlorohydrin than the crude stream treated. In the separation processes, impurities can collect in various parts of the distillation towers or the equipment located downstream from the distillation tower, such as condensers, accumulators, and pipes. As these byproducts and unreacted species flow through the equipment, they can and typically do foul the equipment by undergoing reactions which form a gum. Consequently, the process must be shut down from time to time to clean out the fouled equipment. It is believed that the fouling is due largely to polymerization of one or more impurities distilled and separated from epichlorohydrin.
In an effort to solve this problem, various chemical ingredients have been proposed to inhibit the fouling of equipment used to isolate epichlorohydrin. These ingredients include 2,6-ditertiarybutyl-4-methylphenol, 2,6-di-tertbutylphenol, or mixtures thereof commonly sold as antioxidants under the name Ionol, Ethyl 733, and Univox. However, these ingredients were only somewhat effective in retarding the fouling of epichlorohydrin equipment. In U.S. Pat. No. 4,944,847, a C.sub.3 -C.sub.9 linear or branched alkyl substituted catechol, preferably a 4-tertiarybutylcatechol, was proposed as an antifoulant to technically outperform the hindered phenols previously described. Unlike the hindered phenols, this material is quite expensive due to its limited availability. Thus, there remains a need to find an alternative antifouling ingredient which is both technically and commercially competitive.